What do you use for bypass caps in the 22/25uf 50v range?

[leewongfei]

Hi everyone! I am low on bypass caps and am in need of a brand/source of new caps. What brands do you use for your 22/25uf 50v bypass caps? Where do you source them?

Sprague goes for$4-7 per, twice as much as the IC caps I currently use. Nichicon used to cost around $1 per, but they are impossible to find. I started to use 22uf 50v IC caps at $1.15 per, but I'm not 100% comfortable with them as a company. Mojotone has a Kingcap, and MOD has their own generic cap but I don't know who the manufacturer is for either. I've repaired amps with cheap capacitors that spit electrolytic all over the can and boards, hence why I'm hesitant on MOD and Mojotone. F&T is a 25uf 100v but I'm not sure changing it to that range is the best idea. Any advice or information would be greatly appreciated. Thanks in advance!

 

[sds1]

If the 100V part fits I don't see why you wouldn't use it.

Axial parts are getting harder to find.

Vishay still makes some axial parts for a reasonable price, check Mouser for more info

 

[Powdog]

Just pay for the Sprague Atoms. The fact that you’re not comfortable using the others should justify the price. Everything about replacing a cheap part that has failed sucks.

 

[Huddy]

MODs are fine.

 

[corliss1]

I've went through a few hundred of the MOD caps now with no issues.

No reason to not trust IC - one of the biggest cap makers on the planet. Don't let the internet drama around them, which is sooooo overblown, take over your brain.

 

[2L man]

In new builds I use Radial Electrolytes. I drill holes to circuit board and install cans legs up. Sometimes turrett placing must be brought closer in. Often there are two or three different height/diameter ratios and the bigger diameter electrolytes are low enough.

Nowadays Radial 105C 10 000h... can be cheaper than 85C 1000h Axials. I did electronic work 42 years and IME electrolyte quality often define electronics life. Sometimes when "switching technology" began to fail after few years I did replace better rating electrolytes to which had not broke and then they did function easily 10 years sometimes up to 20 years until whole system was outdated.

 

[Lorenz1973]

Sprague Atoms, for a Princeton reverb 25µf 25v at €2,8 at Banzai De. The 50v costs €4,4 but 25v is enough for my project.

 

[King Fan]

Nichicons were great, and inexpensive, but the axial ones seem to be disappearing. Agree with @sds1 -- there's no reason to avoid a higher power rating if the cost is OK. You can go 20, or 50, in a car that's rated for 100mph. And I agree with @corliss1 that IC phobia is not warranted by an issue from years ago.

But wait... news flash!!! Mojotone's web site says "F&T is Mersen now" -- re-branding, I guess -- and this Mojo page suggests the price structure in your 25uF neighborhood.

 

[printer2]

Just to comment on the voltage rating of the cap. Put a 22uF 6V cap off the cathode of a triode, measured the gain, replaced it with a 350V cap, the circuit measured the same. Not that I expected differently but there was a question about it way back when.

 

[schmee]

The Mod or Black 25uf 50V are fine. $.40 to $.65 each

 

[SerpentRuss]

They're not in the signal chain and 25 volts caps are very generous for most applications, especially in the preamp section where 10volt would do fine. You need to look at all the voltages in caps of that value and configuration however to see where the most choices and the best bargains are. Filter for voltage last. I find the trick with mouser is to find items that have a 10 count discount and buy 10 at a time.

I think the IC you mentioned is a decent 22uF, 50V for $1 apiece in quantity.

https://www.mouser.com/ProductDetail/Cornell-Dubilier-CDE/226BPA050M?qs=3tP%252BN51vMXcJ1vwbntMzLA%3D%3D

 

[tubedude]

If we're talking about the cathode caps in the preamp stages, they are definitely in the signal path. The 25uF value is much larger than it needs to be, and an electrolytic in that position compromises your signal.
Use a metalized film cap in the 4 to 10uF range. They sound better and will never degrade like electrolytics do, and will never need to be replaced.
Here is an example from the Parts Express website:

 

[SerpentRuss]

If we're talking about the cathode caps in the preamp stages, they are definitely in the signal path. The 25uF value is much larger than it needs to be, and an electrolytic in that position compromises your signal.
Use a metalized film cap in the 4 to 10uF range. They sound better and will never degrade like electrolytics do, and will never need to be replaced.
Here is an example from the Parts Express website:
View attachment 1251072

I understand that different values of bypass caps have a great deal of influence on tone by changing the frequency response of of the gain stage, but the actual signal does not pass through them, does it? Everything that passes across a bypass capacitor gets shunted to ground. A shorted bypass cap eliminates the bias completely and an open cap will eliminate gain, but I thought quality wasn't really an issue, as long as the value is correct.

Do I need to pay more attention to the quality?

 

[tubedude]

I understand that different values of bypass caps have a great deal of influence on tone by changing the frequency response of of the gain stage, but the actual signal does not pass through them, does it? Everything that passes across a bypass capacitor gets shunted to ground. A shorted bypass cap eliminates the bias completely and an open cap will eliminate gain, but I thought quality wasn't really an issue, as long as the value is correct.

Do I need to pay more attention to the quality?

When you look at the signal path , how does the signal get to the tubes plate? There's no connection. The plate current is drawn through the cathode to the plate. Plate current is cathode current. The voltage sitting on the grid just influences the cathode current. So your signal passes through the cathode cap.
All an amplifier does really is modulate the power supply current. So your power supply components contribute directly to your tone also.

 

[SerpentRuss]

When you look at the signal path , how does the signal get to the tubes plate? There's no connection. The plate current is drawn through the cathode to the plate. Plate current is cathode current. The voltage sitting on the grid just influences the cathode current. So your signal passes through the cathode cap.
All an amplifier does really is modulate the power supply current. So your power supply components contribute directly to your tone also.

Ah, I get it now. Thanks. I keep forgetting electrical flow is from negative to positive

 

[gabasa]

Over the last while I've switched almost entirely to Jupiter's Cosmos electrolytics. So far, no issues!

 

[Nicko_Lps]

What brands do you use for your 22/25uf 50v bypass caps? Where do you source them?

There should be very small audible difference from 22uf to somewhat smaller but poly caps. As @tubedude mentioned above, try smaller ones but poly or metalized, will last you a lifetime and will filter more noise because they operate in higher frequencies.

If you dig all over the internet you will find 22uf NON electrolytics at low voltage.

 

[2L man]

Cathode bypass capacitor effect to "global negative feedback". Without bypass cathode voltage change when anode current change to the same direction the Grid drive signal and gain come lower. Capacitance can be used to make it a high pass filter. 470nF is effective for guitar fretboard frequencys bypassing highest ~1kHz notes almost fully but to low E 82Hz there come about 6db less output.

I recall 25uF will fully bypass all guitar frequencys.

 

[GlideOn-Designs]

Ironically I've had Sprague Atom 100v caps fail in the power tube bias section yet not Illinois / IC caps.

 

[Mr Ridesglide]

One supplier had a sale once - ridiculous one like 20% off all caps. I spent a few hundred dollars, and until I needed radial caps for a project, I hadn't bought a cap for many years. Stocked up on the usuals for this room. I think I got 50 of the 25/50's and still have probably enough for a few more years - hadn't thought of the fact that they have a life span.... doh!